Asphalt composition



Patented Jan. 15, 1952 .ASRHALT POSIT ON Frederick Fow kes, Oakland, Qalifi, assignor to Shell Development Company, San Francisco, Calif., a corporation of Delaware 1 9 Dra ing application Ma h 2?; 9 8 e f'i l 16,??

10 Claims. (01.106-281) Th s i veni en r ates bi m nous 9 11 1 tien ha g mpr e adhes on h taeter i s The prevention of stripping of asphalt from aggregate is a perennial problem which has received a great amount of attention, especially durn e n we Th i fl en 9? ate 611 th destruction of asphalt coating has been studied, and var ou art al ut ns a e e sug e e The 9W? Pr pa att c s h ve be n 9 m??? t surface of the solid with an agent designed to reduce the stripping action or, secondly, to in-- eer e e e en n in t e ee e te eleeemplieh the same purpose. Qombinations of these methods have been attempted with partial "success. Acids have been incorporated in the asphalt, and the aggregate has been sprayed with an alkali so that metallic soaps are formed in situ during or after the coating operation. In most cases, however, the soaps which result are dispersible in water or have little or no effect upon the stability of the bituminous composition.

One of the most effective types of additives employed in asphalt comprises various oleophilic high molecular weight amines. These have been used either alone or in conjunction with yarious oil-soluble acids, such as the higher fatty acids. In .certain cases, the latter combination appears to be initially effective. However, due to the formation of amides between thetwo agents, their cooperative effect .substani-ally diminishes, es pecially if the asphalt is subjected at any time to heating. Since asphalt is normally shipped from the refinery to a building or road-laying si e in he ted tank ca th s ami e .fermatien constitutes a ser o imit io upon t e tee ,ef this combination of additives.

It is an objectof the present invention to prov de a p a t com esit e av n im reved ad hesien c a acteris cs a xhi i ineeut en n anti-stripping properties.

Now, in acc rdan e with the presen ention it has bee f n at a rigid inter re may be formed be een a Wet a e ate and a s ha t by p imi g th a re te it an e i nenredueine agent and subsequen y seeiins re iee aggregate ith e .eeehelt senamine, especially apol-yamine condensation prod:- ust of acrolein and ammonia, as more fully described hereinafter.

Further in accordance with this invention, it has been found that the resulting compositions have advantageous structural characteristics, such as resistance to disintegration by weather, temperature changes or traffic.

' In summary, the present invention primarily com-prises the formation of an organic ammonium salt insoluble in either water .or asphalt at an asphalt-wet solid interface, resulting in the formation of arigid interfacial film which increases the adhesion of the asphalt -:to the solid.

' {Ihenature of .the rigid film referred to above has not been ascertained, in view of the difiicul ties attending such an investigation. :It is be: lieved that the rigid film consists essentially of a network of crystals of the organic ammonium salt, the interstices of which are filled with a rigidly held film of asphalt. The exact reason for the inflexiblenature of the resulting structure has not been determined, but it is believed to be caused by the substantial insolubility of the organic, ammonium salt in the asphalt phase as well as in any aqueous phase which may be present.

The nature of rigid films so produced isreadily demonstrated by the following technique: A drop of asphalt containing about 1% octadecylamine i dropped in o a beake .Q wate e te in an anion-active a ent. su h as ,0 m ar S t potassium dihydrogen phq ha e- A p inted stirring rod .is touched against the side of the asphalt dro audthen is p led u wa s The surface of the drop extends to form' a pointed projee ien w ich rema n d t d r a pe o which may be from about thirty seconds to' as much as several days. If theexperimnt is reeete wit asphal h eh does i eei t e amine th d te tion Jef h 'eeph d is very ern. .eea y n ee eree e the t n rtion thereof receding back into theboldy of the ,drop Within le s thene e nd- A sim la e e ti e tein e i th ac d phos ha is it ed from the water in, which the asphalt drop is plac d W The significance of the .rigid film so produced is 9 e .ti e. im er e e in s abili n a ph egere at eempe's qn a a t d l erio s e t f Qj wete The ad a ta es t be ained thereby may be det ermined by the standard as.- phalt testing methods, several of "which are .described hereinafter. The rigidity .of'the inter. facial films formed as described above appears to be a major factor resisting the stripping action of water. The change in surface spreading pressures of asphalt containing amines is particularly striking when such asphalts are spread as a film on an aqueous surface containing an anion-active agent.

The amines which may be used in accordance with the present invention are those normally found to be partially effective as adhesion agents. These have been fully described throughout the art and include aliphatic amines, particularly those having at least 14 carbon atoms and especially the long-chain primary amines. Secondary and tertiary amines which are oleophilic in character may be used for the present purpose, although primary amines are preferred. Polyamines such as hexamethylene tetramine are especially satisfactory. Two preferred members of this group include amines derived by the ammonolysis of chlorinated paraffin wax, and the polyamine condensation product of acrolein and ammonia. The latter material is especially useful when hydrogenated and reacted with less than an equivalent amount of an organic oleophilic acid, e. g., a fatty acid, such as oleic acid.

The amine may be incorporated in the asphaltin minor amounts, e. g., from about 0.25% to, about 2%, preferably from about 0.5% to about 1.0%, by weight of the asphalt. However, higher or lower concentrations may also be used in some cases.

The aggregate is to be primed with an anionproducing agent which is soluble in water. The priming may be effected by spraying or otherwise wetting the aggregate. This is conveniently carried out at a mix plant or at the crushing mill, especially when the crushed aggregate is carried away from the grader on a continuous belt, so as to permit a spraying device to be situated above the belt.

The anion-active agent may be any material, either organic or inorganic, which is capable of producing an anion which in turn willform an organic ammonium salt with the amine present in the asphalt. Suitable agents for use in priming the aggregate are phosphates, especially potassium acid phosphate; chromic acid or chromates, especially of weak bases; citric acid and citrates of weak bases; other organic acids such as gallic and tartaric acids; sulfates of weak bases such as ammonium sulfate; alkali metal bicarbonates such as sodium bicarbonate; proteins, such as egg albumen, casein, etc.; nitrates of weak bases such as ammonium nitrate; and organic sulfonates such as the petroleum sulfonates obtained from the so-called green acids" and the aromatic sulfonates.

The anion-active agent may be applied in the form of a dilute solution. Excellent rigid films are produced by the application of 1-5% (based on the weight of the aggregate) of aqueous solution which is 0.01 to 0.1 molar in anionic content. In the case of a basic aggregate such as limestone, somewhat increased amounts of the priming solution may be necessary for the double purpose of neutralizing the aggregate surface and forming the organic ammonium salt.

The bituminous materials to which the present invention applies especially include pyrogenous asphalts, blown asphalts and the natural asphalts and asphaltites. Other pitches and heavy residues such as wood tar and coal tar derive the same benefit.

The solids which may be treated according to the present invention may be plain surfaces such as glass, wood, cement or plaster or preferably may be the standard aggregates employed in the production of asphalt structures such as roads and airport pavings. The method produces rigid films regardless of the character of the aggregate, although superior results appear to be obtained with such aggregates as granite and rhyolite.

It has been found substantially essential to prepare the insoluble rigid films in situ as described above. It has been demonstrated that the addition of preformed salts which are substantially insoluble in asphalt or water has only a minor effect on adhesion characteristics. The presence of the rigid films stabilizes the mechanical structure in such a way as to increase the bearing value thereof so as to permit their extended use for strenuous duty, such as in heavy traflic areas.

Especially desirable amines for use in the present invention comprise water-insoluble polyamines obtained by hydrogenating the condensation product of an alpha-beta unsaturated aldehyde and ammonia or an amine. These waterinsoluble polyamines may be in the free state or in the form of organic acid salts or in at least partial amide formation with organic acids.

A particularly preferred group of unsaturated aldehydes which may be used in the preparation of these polyamines comprises acrolein and its homologs. Other members of the group are, for example, methacrolein, alpha-ethylacrolein, alpha-propylacrolein, alpha-isopropylacrolein, the alpha-butylacroleins, and their homologs.

Primary amines or, more preferably, liquid ammonia may be condensed with the above types of aldehydes, preferably at a temperature between 70 to about 150 C. In order to improve the stability and color of the resulting products, it is preferred that they be hydrogenated following their preparation. These polyamines are usually viscous oils containing up to about 10% of oxygen. The average molecular weight generally is from about 2 /2 to about 6 times the molecular weight of the unsaturated aldehyde reactant; hence, the polyamines usually have average molecular weights within the range 135 to about 330. The ratio of the molecular weight to the equivalent Weight generally is within the range from about 2.5 to about 4. In order to form a water-insoluble product, these amines may be treated with a higher fatty acid such as oleic acid to form a complex mixture of salts and partial amides. A typical reaction may employ temperatures from about 100 to 300 C. for a period from about five minutes to three hours. Other acids may be used for this purpose, such as naphthenic acids or tall oil.

A typical preparation is as follows:

22 parts of acrolein were mixed with parts of anhydrous liquid ammonia at a temperature of 60 to 70" C. A clear mobile liquid was formed. The excess ammonia was removed from the mixture by allowing the mixture to warm to room temperature in an open vessel. The residue, amounting to 28 parts, was dispersed in 105 parts of absolute ethanol. 5 parts of Raney nickel catalyst were added to the dispersion and the mixture was subjected for one hour to the action of hydrogen gas under a pressure of 1000 pounds per square inch at C. Low boiling material, chiefly ethanol, was removed by disstillation under reduced pressure, leaving 18- assi ned parts of a viscous, water-soluble 611 having the following characteristics:

Molecular weight 228.00

Equivalent weight 70.00 Per cent carbon 61.38 Eercent nitrogen 19.25 Per cent hydrogen- 1. 10.80 Per cent oxygen 8.57

The polyamine hydrogenated product thusobtained is water-soluble. Inorder to insolubilize it, oleic acid is heated therewith at 240 C. for minutes to form mixed reaction products principally consisting of oleic acid salts and amides of the polyamine. Three such products were The following examples illustrate the process of the present invention:

Example I A soda rhyolite aggregate graded between (100% passing) and (100% retained) sieves was sprayed with 2% by weight of water. In certain cases, as indicated in the tables below, potassium acid phosphate or chromic acid were present in the water. Six parts by weight of medium curing San Joaquin Valley asphalt was mixed with a hundred parts by weight of the primed aggregate. Prior to mixing with the aggregate, the asphalt had been heated for seven days at a temperature of 120 0. As noted in the examples which follow, various amines were present in some of the asphalts employed. The coated aggregates were allowed to stand in the open air at about room temperature for one hour after which they were covered with distilled water for twenty hours at room temperature. The percentage of the aggregate surfaces still coated with asphalt after this treatment was then estimated. In the first case, an acroleinammonia condensation product, which as hydrogenated'and in an amide formation with onethird of an equivalent weight of oleic acid, was employed as the asphalt additive. obtained are given in the following table:

The above test was carried out as described, using Cit-C18 substantially straight-chain amines as the asphalt additive. The results obtained are given in the following table:

Percent Amine in Percent Coating Sp t Priming Solution Retained 0.75 Water None 0.05 M 0103 10 0.75 0.05 M 0:03 80 I claim as my invention: 1. An asphalt composition comprising as its predominant ingredients an asphalt, a wet ag- The results 6. gregate and a minor amountof'a-salt of 'a long chain aliphatic hydrocarbon amine and an alkali metal amine and water-soluble inorganic acid phosphate, said salt being substantiallyinsoluble in asphalt and in water and being present at least in an amountsumcient to improve the-adhesion of the asphalt to said wet aggregate.

2. An asphalt composition comprising an as phalt, a wet aggregate and a salt of a long chain aliphatic hydrocarbon amine and chromic acid, said salt being substantially insoluble in asphalt and in water, and bein present at least in an amount sufficient to improve the adhesion of the asphalt to said wetaggregate.

3. An asphalt composition comprising an .asphalt, a wetaggregate and an acid phosphatesalt of the hydrogenated polyamine condensation product of ammonia and acrolein, said condensation product being the form of a partial amide with oleic acid, said acid phosphate salt thereof being substantially insoluble both in asphalt and in water, and being present at least in an amount sufficient to improve the adhesion of the asphalt to said wet aggregate.

4. An asphalt composition comprising an asphaltic material, a solid and, at the interface therebetween, a salt selected from the group consisting of phosphates and chromates of a long chain aliphatic hydrocarbon amine being substantially insoluble both in water and in asphalt, and being present at least in an amount suflicient to improve the adhesion of asphaltic material to the solid.

5. An asphalt composition comprising an asphaltic material, a wet solid and small amount of a reaction product of a long chain aliphatic hydrocarbon amine with a water-soluble acidacting agent having a polyvalent anion and having only a monovalent cation, said amount being sufficient to improve the bonding power of the asphalt said reaction product being insoluble in asphalt and water and forming a rigid interracial film between the solid and the asphalt.

6. An asphalt composition consisting essentially of an asphaltic material, a solid and, at the interface therebetween, the reaction product of octadecylamine and potassium dihydrogen phosphate, said reaction product being substantially insoluble both in water and in asphalt and being present at least in an amount suflicient to improve the adhesion of asphaltic material to the solid.

7. An asphalt composition consisting essentially of an asphaltic material, a solid and, at the interface therebetween, a salt reaction product of a long chain aliphatic hydrocarbon amine and potassium dihydrogen phosphate, said reaction product being substantially insoluble both in water and in asphalt and being present at least in an amount sufficient to improve the adhesion of asphaltic material to the solid.

8. An asphalt composition comprising an asphaltic material, a solid and, at the interface therebetween, a salt reaction product of octadecyl amine and chromic acid, said reaction product being substantially insoluble both in water and in asphalt and being present at least in an amount sufiicient to improve the adhesion of asphaltic material to the solid.

9. An asphalt composition comprising an asphaltic material, a solid and, at the interface therebetween, the salt reaction product ofan oleic acid partial amide of a hydrogenated polyamine condensation product of acrolein and ammonia with potassium dihydrogen phosphate,

said reaction product being substantially insoluble both in water and in asphalt and being present atileast in an amount sufilcient to improve the adhesion of asphaltic material to the solid.

10. An asphalt composition comprising an asphaltic material, a solid and at the interface therebetween an amine salt of a water-soluble acid-acting agent, wherein the amine is selected from the group consisting of (1) a long chain aliphatic, hydrocarbon amine and (2) an oleic acid partial amide of a hydrogenated polyamine condensation product of acrolein and ammonia and theacid-acting agent is composed of a polyv REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,191,295 Dohse et a1 Feb. 29, 1940 2,370,386 Anderson et a1 Feb. 27, 1945 2,386,163 Holmes et a1 Oct. 2, 1945 I 2,438,318 Johnson Mar. 23, 1948 FOREIGN PATENTS Number Country Date 513,944 Great Britain Oct. 26, 1939 568,385 Great Britain Apr. 3, 1945 

10. AN ASPHALT COMPOSITION COMPRISING AN ASPHALTIC MATERIAL, A SOLID AND AT THE INTERFACE THEREBETWEEN AN AMINE SALT OF A WATER-SOLUBLE ACID-ACTING AGENT WHEREIN THE AMINE IS SELECTED FROM THE GROUP CONSISTING OF (1) A LONG CHAIN ALIPHATIC HYDROCARBON AMINE AND (2) AN OLEIC ACID PARTIAL AMIDE OF A HYDROGENATED POLYAMINE CONDENSATION PRODUCT OF ACROLEIN AND AMMONIA AND THE ACID-ACTING AGENT IS COMPOSED OF A POLYVALENT ANION AND ONLY MONOVALENT CATIONS, SAID AMINE SALT BEING SUBSTANTIALLY INSOLUBLE BOTH IN WATER AND IN ASPHALT AND BEING PRESENT AT LEAST IN AN AMOUNT SUFFICIENT TO IMPROVE THE ADHESION OF THE ASPHALT TO THE SOLID. 